The present invention relates to calcium- and phosphate-containing compositions for use as mouthwashes or dental rinses. In particular, it relates to solutions supersaturated with calcium and phosphate, their preparation and use.
By xe2x80x9csupersaturatedxe2x80x9d with calcium and phosphate is herein meant that higher concentrations of calcium ions and orthophosphate ions are present in the solution than would be present in a saturated solution of those ions.
British patent specification no. GB 1 090 340, published in 1967, discloses compositions for rehardening dental enamel comprising fluoride, calcium, phosphate and sodium chloride which yield, on contact with saliva, supersaturated solutions to form hydroxyapatite. Because saliva is required to form the supersaturated solution, the preferred compositions are in the form of confectionery such as chewing gum. However, it is known that, under most circumstances, saliva is already supersaturated with calcium and phosphate. No disclosure is given of how to make a supersaturated solution ab initio which can then be used effectively in the form of a mouthwash or dental rinse. Furthermore, no mention is made of the possibility of excluding fluoride; or of the formation of octacalcium phosphate by the supersaturated solution in the saliva. In any case, in the absence of or where there is a significantly reduced mount of saliva, these compositions would not work as described.
A supersaturated solution is disclosed in U.S. Pat. No. 5,427,768 which is supersaturated with calcium phosphate and carbon dioxide and used to deposit apatite on the teeth. However, in this case, the supersaturation is caused by release of carbon dioxide, and carbonate is absorbed by the teeth which results in a deposited mineral phase with decreased resistance to dental caries.
British patent specification no. GB 1 408 922, published in 1975, discloses an oral treatment pack which comprises two phases for sequential application to teeth, the isolated phases comprising calcium (50 to 35000 ppm) and phosphate (50 to 40000 ppm) compounds, respectively. However, there is no disclosure or teaching regarding how to make a single phase, supersaturated solution within these concentration ranges which cover four orders of magnitude. Indeed, Example 3 thereof teaches two phases which, if mixed, would result in immediate precipitation of calcium phosphates.
A further solution containing calcium and phosphate is disclosed in British patent specification no. GB 1 509 977, published in 1978. This solution comprises one component containing calcium ions (at least 30 ppm) and another component containing at least 100 ppm fluoride, one or both components also containing phosphate ions (at least 0.1M) such that on mixing the components hydroxyapatite can be deposited therefrom on teeth. However, such solutions are not stably supersaturated (indeed, this patent teaches that the phosphate ions can be incorporated only in the solution containing calcium ions (at low concentration) which would not allow for the preparation of a stable, non-precipitating, supersaturated solution), and contains greater fluoride than considered to be clinically safe if accidentally swallowed. Again, no reference is made to producing octacalcium phosphate deposits.
On the other hand, the present invention relates to an aqueous solution suitable for use as a dental rinse or mouthwash, which solution is supersaturated with respect to calcium phosphate(s) and which solution further comprises a stabilising agent such as sodium chloride (NaCl).
Although, as previously mentioned, it is known that, normally, saliva is supersaturated with respect to calcium and phosphates, the supersaturated solutions of the present invention contain significantly higher concentrations of those ions. Since the degree of supersaturation of saliva is variable from individual to individual, it is not possible to state definitively how much more supersaturated are the solutions of the present invention, but they may in many cases contain of the order of from 5 to 10 times the concentrations of calcium and phosphate ions than normal saliva.
The present inventors have disclosed (Gerodontics 3, 47-50 (1987)) the remineralisation of carious lesions in elderly patients using an experimental regimen which included mouthwashing with a solution comprising 5 mM Ca, 3 mM PO4 and 0.25 mM (5 ppm) fluoride, stabilised by NaCl, at pH 7.0. No other uses of the solution were mentioned and no details concerning the preparation of the solution were given other than that xe2x80x9ctwo stock solutions were stored separately and mixed in proper volumes immediately before usexe2x80x9d.
The supersaturated solutions of the present invention are required to be prepared just prior to use due to the degree of supersaturation thereof and the risk of precipitation of calcium phosphate (mineral) therefrom.
Accordingly, the present invention provides a formulation suitable for use as a dental rinse or mouthwash, which formulation comprises:
(a) a calcium component (calcium stock solution) which itself comprises an aqueous solution of calcium ions and stabiliser; and, associated therewith but separate therefrom,
(b) a phosphate component (phosphate stock solution) which itself comprises an aqueous solution of phosphate ions and stabiliser wherein the calcium and phosphate are present in amounts sufficient to form, on mixing, a supersaturated solution thereof, as described hereinbelow.
The present invention therefore specifically provides a multi-component formulation suitable for use as a dental rinse or mouthwash, which formulation comprises:
(a) a calcium component (calcium stock solution) which itself comprises an aqueous solution of calcium ions having a concentration in the range of from about 4 to about 80 mM and from about 40 to about 400 mM stabiliser; and, associated therewith but separate therefrom,
(b) a phospate component (phosphate stock solution) which itself comprises an aqueous solution of (ortho)phosphate ions having a concentration in the range of from about 1 to about 64 mM and from about 40 to about 400 mM stabiliser
whereby, on mixing, the components form a solution supersaturated with respect to calcium phosphate(s).
The supersaturated solutions of the present invention remain stable at least for the length of time and under normal conditions of their use. By this is meant that the supersaturated solution remains substantially supersaturated with respect to calcium and orthophosphate ions for the normal time the solution is rinsed or washed around the oral cavity. After this time, the solution may begin to contain some precipitate of calcium phosphates which would reduce its therapeutic effectiveness. Therefore, conveniently, the solution may remain supersaturated in the oral cavity for up to about five minutes, especially up to 2-3 minutes and necessarily up to about 1 minute, all measurements therefore taken at body temperature. It will be understood that, at lower temperatures such as room or ambient temperature, the supersaturated solution will remain so for significantly longer periods such as of the order of up to 2 hours, especially up to 1 hour and necessarily for the length of time taken to use the supersaturated solution just mixed as a dental rinse or mouthwash which may be in the range of from about 3 minutes to about 15 minutes.
Preferably components (a) and (b) do not, respectively, contain any phosphate or calcium, although minor amounts (up to 10-20% either wayxe2x80x94less at higher pH and vice versa) could be tolerated.
Preferably, the supersaturated solution has a pH of from about 5 to about 8.0, more preferably of from about 6 to about 7.5, such as about 6.5 to about 7.5; especially preferred is when the pH is about neutral such as 7.0xc2x10.2. The pH of each stock solution component may vary widely: for component (a), it is in the range 1 to 12.5, preferably 3.5 to 8, more preferably 4 to 7.5; for component (b), it is in the range 2 to 13, preferably 4 to 8.5, more preferably 5 to 7.5. The pHs of components (a) and (b) in the case where the pH of the supersaturated solution is to be around neutral are preferably around 4 to 7.5, more preferably 4 to 6, especially around 4; and 5 to 7.5, preferably 7 to 7.3, more preferably around 7.2, respectively.
Preferably, the concentration of calcium ions (total Ca2+ i.e. free and complexed) in the supersaturated solution is in the range of from 2 to about 40 mM, such as 2 to about 21 mM, more preferably in the range of from 2.5 to 16 mM. At around neutral pH, the concentration of calcium ions in the supersaturated solution is suitably in the range of from 2.5 to about 10 mM, preferably 3 to 5 mM, for example, about 3.87, 4.5 or 5 mM calcium ions. Especially suitable is when the concentration of calcium ions is around 4.5 to 5 mM, for example, 4.74 mM particularly to promote formation of octacalcium phosphate.
Component (a) most preferably contains calcium as calcium chloride. Other sources of calcium which have been used in mouthwashes include calcium nitrate, calcium hydroxide or calcium carbonate, optionally including a minor amount of calcium phosphate, dissolved in an acid such as HCI, Preferred sources of calcium are calcium nitrate and calcium hydroxide, but calcium chloride is most preferred. The concentration of calcium ions in component (a) is conveniently double that In the supersaturated solution and therefore suitably In the range of from about 4 to about 80 mM. Preferably, the range is from about 4 to about 40 mM, more preferably 5 to 32 mM, especially 5 to 20 mM, and more especially around 10 mM, for example 9.47 mM.
Preferably, the concentration of phosphate ions (total (ortho)phosphate) in the supersaturated solution is in the range of from about 0.5 to about 32 mM, preferably about 1 to 20 mM such as 1.5 to about 10 mM. At around neutral pH, the concentration of phosphate is suitably in the range of from about 2 to about 6 mM, preferably 2 to 4 mM, for example, about 2, 3, 3.4 or 3.87 mM. Especially suitable is when the concentration of phosphate ions is around 2.7 to 3.4 mM, for example, 2.96 mM to promote formation of octacalcium phosphate.
Component (b) preferably contains phosphate as a mixture of monobasic phosphate with dibasic phosphate. To comply with the much preferred pH of the supersaturated solution (pH=7.0xc2x10.2), the ratio of mono:dibasic phosphate is in the order of about 1:2-1:8, preferably 1:2.5-1:3.5, such as about 1:3. At the higher concentrations of calcium and phosphate in the stock solutions, the amount of dibasic phosphate would increase relative to monobasic phosphate.
Alternatively, a pH adjuster such as alkalimetal hydroxide or ammonium hydroxide or tribasic phosphate such as a tri(alkalimetal) phosphate could be used to deliver the preferred pH of the supersaturated solution. Since the quantity of hydroxide is more difficult to measure than that of dibasic phosphate, It is preferred to use monobasic phosphates and dibasic phosphates. Another alternative is to use a combination of phosphoric acid with a dibasic or tribasic such as tri(alkalimetal) phosphate. Preferred alkali metals in this context are sodium and potassium, especially sodium.
The concentration of phosphates in component (b) is conveniently double that for the supersaturated solution and therefore is preferably in the range of from about 1 to about 64 mM, preferably from about 2 to about 40 mM, such as about 3 to about 20 mM, preferably at the preferred pH ranges about 4 to about 12 mM, more preferably about 4 to about 8 mM, for example, 5.92 mM. The phosphates are preferably incorporated in the form of their sodium, potassium or ammonium salts; more preferably, sodium salts are employed. However, in cases where hypertensive effects of sodium ions are of concern, mono- and di-potassium phosphates may be used.
To permit use of high concentrations of calcium and phosphate, the solutions incorporate a stabilizing agent which comprises one or more salts of innocuous ions such as the cations Na+, K+, NH4+, Mg++ and Sr++, and anions Clxe2x88x92, CO3=, HCO3xe2x88x92, SO4= and NO5xe2x88x92, but preferably comprises primarily sodium chloride or potassium chloride, and most preferably sodium chloride, except when the solution is for use by hypertensive patients.
When present as the stabiliser, the concentration of sodium chloride in the supersaturated solution preferably ranges from about 40 mM to about 400 mM, more preferably 80 mM to 200 mM, such as around 100 mM. The concentration of NaCl is not very dependent upon pH but it is important not to reduce its concentration substantially below this range or precipitation, rather than a supersaturated solution, will result. Alternative stabilising agents may be used provided they are physiologically acceptable, such as other alkali metal halides such as KCl or other compounds having equivalent effect such as ammonium chloride; but NaCl is much preferred The lower end of the range of stabiliser concentration is employed when lower ends of the ranges of calcium and phosphate concentrations are employed, and ice versa.
The amount of stabiliser in each component is sufficient to enable the calcium and phosphate ions to remain in supersaturated solution once components (a) and (b) are mixed. The concentration of sodium chloride (when used in both components) in each component is equivalent to that in the supersaturated solution and therefore preferably ranges from about 40 mM to about 400 mM, more preferably 80 mM to 200 mM, such as around 100 mM. Incorporation of a stabiliser in both components (a) and (b) allows the use of higher-than-otherwise concentrations of calcium and phosphate ions due to the effect of the stabiliser on total ionic strength and thus on the activities of the calcium and phosphate ions (xe2x80x98salt effectxe2x80x99). Increasing the quantity of stabiliser present increases the possible amounts of calcium and phosphate ions which can be present without rapid or spontaneous precipitation. However, due to the intended use of the supersaturated solution as a mouthwash, the amount of NaCl present in each component (a) and (b) should be limited so that the supersaturated solution is approximately isotonic, to avoid irritation or pain in the oral cavity. Preferably, the ratio of NaCl present in component (a):component (b) is in the order of about 1:1.
Since some of the sodium and chloride ions in the stock or supersaturated solutions may arise from: ingredients other than sodium chloride, as guidance, the following amounts of each ion may be present in the supersaturated solution, chloride may be present in the range of from 0 to about 0.5M, preferably 0.05 to 0.3M, more preferably 0.05 to 0.25M, for example 0.103M; and sodium,(ion) may be present in a similar concentration independently selected from similar ranges, for example 0.107M. In the calcium or phosphate stock solutions (a) or (b), both ions may again be present in similar concentrations in the range of from 0 to about 1M, preferably from 0 to about 0.6M, more preferably 0 to 0.5M, for example, 0.098M (Na+) and 0.117M (Clxe2x88x92) in the calcium stock solution (a); and, for example, 0.108M (Na+) and 0.098M (Clxe2x88x92) in the phosphate stock solution (b),
Preferably, the ratio of concentrations of calcium to phosphate in the supersaturated solution corresponds to 1:1 to 5:3; more preferably 4:3 to 5:3 to increase the amount of octacalcium phosphate formed.
The supersaturated solution may also contain other physiologically-acceptable ions. However, due to the formation of a supersaturated solution (as hereinabove described) on mixing, we have surprisingly found that it is not necessary to incorporate fluoride for clinical effectiveness. But if it should be desired to include fluoride, it is present in the supersaturated solution in the range of from 0 to about 10 mM, preferably 0 to 2.5 mM such as 0 to 0.5 mM, for example 0.25 mM. This preferred range corresponds to a maximum concentration of around 50 ppm, preferably around 5-10 ppm. Inclusion of fluoride in the supersaturated solutions of this invention does not require adjustment of calcium and for phosphate Ion concentrations; in these supersaturated solutions, fluoride and calcium fluoride complexes are formed. In prior art solutions, monofluorophosphate is usually formed.
Where fluoride is to be present, it is preferably added to component (b). It should not all be added to component (a). Therefore, about twice the concentration of fluoride must be present in the phosphate concentrate (b) as specified above for the supersaturated solution. The fact that the supersaturated solutions of the present invention are clinically effective in remineralising teeth in the absence of fluoride is surprising, especially given the emphasis on including fluoride in remineralising solutions in the prior art. For example, Koulorides in Experimental Changes of Enamel Mineral Density [in Harris: Art and Science of Dental Caries Research, pp 365-378 (Acad. Press, N.Y., 1968)] showed that, in enamel re-hardening experiments using calcium/phosphate solutions, the addition of fluoride to the solution resulted in a (about) four times increase in hardness of dental enamel compared to similar solutions excluding fluoride.
Another, optional, ion which may be present in the supersaturated solution is zinc, in the range of from 0 to about 1 mM, such as 0 to 0.5 mM, preferably in the range of from 0 to 0.1 mM. Zinc is particularly advantageous in speeding up wound healing and in decreasing the solubility of the mineral (eg. hydroxyapatite and especially octacalcium phosphate) formed. When present, the amount of zinc is preferably chosen so that up to 50 mg, more preferably around 15 mg, is administered per treatment dose.
Where zinc is to be present in the supersaturated solution, it is preferably added to component (a) although it may also be added, at lower concentrations, to component (b). Therefore, twice the concentration of zinc must be present in the calcium concentrate (a) as specified above for the supersaturated solution.
Other, known, additives may be present in the supersaturated solution such as flavoring or colouring agents, or preservatives. Mint flavouring is especially preferred where the supersaturated solution is to be used in xe2x80x98normalxe2x80x99 patients (but it can be an irritant in bone marrow transplant (BMT) or irradiation patients). Of the usual preservatives, sodium benzoate is preferred in concentrations insufficient substantially to alter the pH of the supersaturated solution, otherwise the ratio of mono:dibasic phosphates would need to be adjusted to arrive at the desired pH.
However, other ingredients which have been known in prior art calcium/phosphate solutions are preferably excluded from the formulations of the present invention. Therefore, the aqueous, supersaturated solutions described herein are most preferably substantially free from: carbon dioxide; alcohol; silicate; acetate or other organic acid salts; chelating agent; antinucleating agent; fluorophosphate; and the like.
The solutions (including concentrates; stock solutions and supersaturated solutions) described herein preferably consist essentially of calcium ions, orthophosphate ions, sodium Ions, chloride ions and, optionally, fluoride ions and/or zinc ions in the concentrations already specified, and, if desired, colouring(s), flavourlng(s) and/or preservative(s). More preferably, the solutions are substantially free from any ion or other ingredient which is not normally present in saliva.
The present invention further provides a system for preparing an oral rinse that comprises a supersaturated calcium phosphate solution, said system comprising (a) a calcium stock solution containing calcium ions in a concentration of from about 2 to about 40 mM and sodium chloride or another physiologically acceptable stabilizer in a concentration of from about 40 to about 400 mM; (b) a phosphate stock solution separated from said calcium stock solutions, said phosphate stock solution containing phosphate ions in a concentration of from about 0.5 to about 32 mM; and sodium chloride or another physiologically acceptable stabilizer in a concentration of about 40 to about 400 mM; and (c) means for combining said calcium stock solution and said phosphate stock solution shortly before use thereof to form a supersaturated solution of calcium phosphate.
A preferred system is one wherein the pH of said stock solutions is maintained such that the pH of the supersaturated solution is in the range from about 5.0 to about 8.0. Other preferred features of the system will be appreciated from the foregoing description.
The present invention therefore still further provides a method of preparing a supersaturated calcium phosphate solution for use as an oral rinse, the solution comprising:
calcium in a concentration of from about 2 to about 40 mM;
phosphate in a concentration of from about 0.5 to about 32 mM;
sodium in a concentration of from 0 to about 0.5M;
chloride in a concentration of from 0 to about 0.5M,
which method comprises (a) preparing a calcium stock solution comprising from about 4 to about 80 mM calcium ions and from about 40 to about 400 mM sodium chloride; (b) separately preparing a phosphate stock solution comprising from about 1 to about 64 mM phosphates and from about 40 to about 400 mM sodium chloride, and (c) mixing said stock solutions (a) and (b).
A preferred method is one wherein said calcium stock solution (a) is prepared by diluting a calcium concentrate with sufficient water to form said calcium stock solution; and said phosphate stock solution (b) is prepared by diluting a phosphate concentrate to form said phosphate stock solution.
Therefore, the components (a) and (b) (stock solutions) to be mixed to form the supersaturated solutions according to this invention are preferably provided as two respective concentrates (ie. each to be separately mixed with water to form the respective stock solutions prior to being mixed together to form the final, supersaturated solution or mouthwash).
For example, an optionally flavoured and coloured calcium concentrate may be provided in a container (such as a 25 ml container) which is packaged together with an optionally flavoured and coloured phosphate concentrate provided in another 25 ml container, together with instructions for dilution with, preferably, distilled water.
Therefore, the present invention further provides a formulation comprising:
(a) a calcium concentrate which itself comprises an aqueous solution of calcium ions in the range of from about 8 to about 2120 mM, such as 10 to 2080 mM, preferably 25 to 1300 mM, for example 360 mM, and 0M to 6.5M sodium chloride or equivalent stabiliser as described above, for example about 3.7M; and, associated therewith but separate therefrom
(b) a phosphate concentrate which itself comprises an aqueous solution of phosphate ions in the range of from about 2 to about 1440 mM, such as 4 to 1300 mM, preferably 20 to 780 mM, for example 225 mM; and a stabilising amount of a physiologically-acceptable stabiliser such as an alkalimetal or ammonium halide such as from 0M to 6.5M sodium chloride, for example, 3.71M NaCl;
whereby, on diluting each concentrate with water in a range of ratios of from 1:1 to 1:64, preferably about 1:4 to 1:64 such as about 1:40 (concentrate:water), for example, 1:37 and thereafter mixing the two stock solutions thereby formed in a range of ratios of from 3:7 to 7:3, preferably 4:6 to 6:4, more preferably about 1:1 (calcium stock solution (a):phosphate stock solution (b)), a supersaturated solution is formed which is suitable for use as a mouthwash or dental rinse.
The calcium concentrate preferably contains sodium (ions) in the range specified above for NaCl in concentrate (a), and chloride in a range of from 0 to about 10.7M, for example 4.43M. The phosphate concentrate preferably contains chloride in the ranges given above for NaCl in concentrate (b); and sodium (ions) in the range of from 0 to about 9.38M, preferably 0.05 to 11.4M. such as 0 to 9.5M, for example 4.11 M. Zinc may be present in the calcium concentrate in the range of from 0 to about 640 mM, preferably 0 to 260 mM, such as 0 to 65 mM, for example, 1.9 mM. Fluoride may be present in the phosphate concentrate in the range of from 0 to about 500 mM, preferably 0 to 32 mM, such as 0 to 65 mM, for example 19 mM.
Optionally, colouring(s), flavouring(s) and/or preservatives(s) may also be present, as hereinbefore described.
The package preferably contains patient instructions (i) separately to mix the contents of each of the above-mentioned 25.0 ml containers with 925 ml of water (for a final volume of 950 ml [one U.S. quart]) or 13.2 ml volumes of concentrate to be diluted to form 0.5 l stock solution; (ii) then to mix at least 8 ml of each preferably in a ratio 1:1 but no less 30% calcium stock solution and no more than 70% calcium stock solution; and (iii) how to use these final, diluted, supersaturated solutions as a mouthwash or rinse for the oral cavity.
However, more preferably, the stock solutions (components (a) and (b)) are provided ready-made so that the patient or medic who is to administer the supersaturated solution only has to mix the two components to form the supersaturated solution, thereby avoid the dilution step. Conveniently, therefore, the stock solutions (a) and (b) are provided in separate, unit dose containers such as sterilised, hermetically-sealed 15 ml containers such as those available from Rommel A.G. (Stuttgart, Germany).
Very conveniently, packages may contain multiples of thirty doses with instructions for an appropriate treatment programme as herein described. For example, for OTC use, a pack may contain thirty doses as a month""s daily treatment, or for clinical use such a pack may comprise a week""s treatment. Alternatively, for the clinic, a pack may provide 120 doses comprising a month""s treatment, depending upon the treatment programme to be followed.
Dental caries is an ubiquitous problem, particularly in elderly patients. The predominant forms of dental caries in elderly patients are root surface and recurrent carious lesions. The supersaturated solutions of the present invention have been found to have a particularly beneficial effect when used as part of a multi-component preventative treatment programme. This treatment programme aims simultaneously to increase tooth resistance, decrease the acid attack rate and enhance the intra-oral physiological maintenance processes. For example, the supersaturated solutions are preferably used in conjunction with treatment components selected from:
A. Oral hygiene: selected from flossing, standardised tooth brushing with fluoride toothpaste and cleaning of tooth surfaces with cotton swabs. Daily use of fluoride toothpaste is to maintain the fluoride levels obtained from step B below;
B. Topical fluoride applications: for example, self-administration of fluoride gel by means of custom-made trays of soft plastic (such as Mouthguard(R) material) e.g. neutral sodium fluoride gel containing xc2xd-1% F. The fluoride application is preferably followed by the mouth being thoroughly rinsed with water to remove residual gel and prevent swallowing of fluoride; and
C. Salivary gland stimulation: for example, by a non-sweetened gum for patients with xerostomia to stimulate salivary secretion.
It is especially preferred that such a preventative treatment programme should be followed before restorative procedures are undertaken in highly caries-susceptible patients. The remineralisation of some lesiorns will facilitate preparation procedures by strengthening the tissues. Also, the sensitivity of the teeth is decreased as the lesion rehardens and exposed dentinal canals close. Furthermore, it is desirable to improve the chemistry of sound tooth surfaces before major reconstructive or restorative work is begun especially since many remineralised lesions may not need to be restored, unless the patient requests restoration for aesthetic reasons.
Treatment using the supersaturated solutions in conduction with component B has been found to be especially beneficial, particularly in cancer patients. Cancer, in all its forms, is highly prevalent in present-day society, and many of the treatments associated with the various forms exhibit severe side-effects. For example, of the one million people in the United States who develop cancer annually, over 400,000 individuals suffer oral complications from their cancer therapies. Additionally, there are 25,000 individuals per year who develop leukaemia. Unfortunately, most cancer treatments affect normal tissues as well as diseased cells. As treatments become more intensive and more successful, their effects on xe2x80x98normalxe2x80x99 tissues have increased, and the oral cavity is frequently the site of severe side-effects.
The oral complications of cancer therapy are, at minimum, painful and, at their most severe, life threatening. These oral side-effects (particularly in patients undergoing chemotherapy and radiation therapy for head and neck cancer including Hodgkins disease and lymphomas) include mucositis, xerostomia, osteoradionecrosis, candidiasis and secondary infections such as herpes. Chemotherapeutic drugs also cause a variety of symptoms which may discourage eating, such as stomatitis, sore throat, change in taste sensation, stomach cramping, feeling of fullness, nausea, vomiting or diarrhoea. Malnutrition is, therefore, a common consequence of the oral complications. Other side effects include monoliasis, dysphagia, tooth hypersensitivity and rampant dental caries.
For example, bone marrow transplantation (BMT) has been found to be successful in the treatment of leukaemia, lymphoma and some solid mass tumours. Prior to a bone marrow transplant, intensive chemotherapy and total body irradiation (for allogenic BMT patients) is administered to the patient in an effort to destroy all cancer cells, The dosages must be so high that the bone marrow is destroyed, leaving the patient wholly dependent on supportive care for defence against infection until the new marrow engrafts and starts to function.
This intensive treatment places the BMT patient in need of dental intervention, since it depresses the patient""s immune system. The majority of BMT patients who die do so as a result of an infection. Reverse isolation and prophylactic antibiotics are effective in preventing microbial infections except or those infections originating in the mouth. Thus, microorganisms can enter the bloodstream through ulcerations of the oral mucosa, resulting in septicemia and, in many cases, death. Studies have shown that 25% of the deaths from infections were of oral origin (as evidenced by, for example, Research Report on Leukaemia, prepared by the Office of Cancer Communications, National Cancer Institute, NIH Publication No. 88-329, 1988; and Epstein, J. B. in Infection prevention in bone marrow transplantation and radiation patients, NCl Monogr. 9 73-85, 1990).
Mucositis is therefore a common consequence not only of (high dose) radiation therapy but also in patients undergoing bone marrow transplantation. This painful condition appears three days post-induction therapy and usually continues until engraftment occurs. The pain is often so great that patients cannot eat and require high-dose morphine. This further debilitates the patient so that total parenteral nutrition is necessary to maintain nutritional levels. Mucositis is caused by non-specific inhibitory effects of the chemotherapeutic agent and radiation on mitosis of the rapidly-dividing basal epithelial cells. Atrophic changes and, eventually, ulceration are a result of this reduction in the renewal rate of basal epithelial cells. The loss of integrity of the epithelium provides a portal for the entry of oral micro-organisms at the time of maximum myelosuppression (the nadir). Oral flora have been found to be the most frequent source of sepsis in granulocytopaenic cancer patients. (NIH, ibid). Non-keratinized mucosa is more vulnerable to chemotherapeutic agents than keratinized mucosa; thus, the highly vascular lining of the floor of the mouth is a common site of entry for oral flora.
Additionally, degenerative and vascular changes in the submucosa, xerostomia and reactivation of latent viruses directly affect the epithelium. Local irritants such as ill-fitting dental appliances, cracked or rough restorations may further compromise the oral mucosa.
Although chlorhexidine has been shown to be useful in the prevention of bacterial and fungal infection, there are no consistent findings in the value of chlorhexidine in reducing mucositis in cancer patients. It probably works on the secondary microbial initiation of already-affected tissue, The problem with its use is that, once mucositis starts, the alcohol content of chlorhexidine preparations makes it difficult for the patient to use even at one-half strength. It is difficult to force the patients who are experiencing severe pain and who are already on morphine to use something that increases their pain.
Many of these side-effects can be minimised with a rigorous preventative regime. In conjunction with oral preventative care, chemical enhancement of the oral environment is essential to maintain the mucosal barrier intact. It has now surprisingly been found that chemical enhancement with the supersaturated solution of the present invention, preferably in conjunction with a multi-component treatment programme such as described above, is effective in decreasing mucositis and increasing survival and recovery. The present supersaturated solutions are effective in treating or preventing both the soft tissue and hard tissue problems or side effects mentioned above.
The supersaturated solutions of the present invention are therefore useful in the treatment or prevention of any disease, patient or condition which requires (a) remineralisation or maturation of oral hard tissue (since these solutions substantially enhance the natural, ongoing remineralisation process); and (b) anti-inflammatory, including anti-mucositis, and anti-infective, including anti-septicaemic, treatment of periodontal, soft tissue. The soft tissue effects of these solutions are particularly unexpected and include positive effects on the gums, soft and hard palates, tongue and mouth floor. Inflammation, ulceration, erythema and eruptions of the mucous membrane may all be treated or prevented with these supersaturated solutions.
It is therefore visualised that the following patient groups will benefit from the use of the supersaturated solutions according to the invention:
Oncology patients undergoing radiation therapy and/or chemotherapy both during treatment and after treatment for as long as salivary function is impaired (months to years);
Bone marrow transplant patients who often develop fatal infections in the oral cavity during and after treatment. The supersaturated calcium/phosphate mouthwash decreases mucositis and increases survival and recovery, sparing the patient pain and discomfort and decreasing hospital stay. In patients suffering from graft versus host disease, the changes to the salivary glands and oral mucosa can last for years and are very painful;
Patients suffering from medical conditions in which salivary secretion is reduced or absent (xerostomia). Specific examples include Sjxc3x8gren""s syndrome, various connective tissue degenerative diseases, and congenital absence of salivary glands;
Patients with decreased salivary functions resulting from the administration of various medications, which as a side-reaction causes impairment of salivary function (psychiatric conditions, high blood pressure, xe2x80x98dry-mouthxe2x80x99 reactions to medicines etc.);
AIDS patientsxe2x80x94to manage their severe mucositis and monoiliasis which occur in advanced stages of the disease;
Patients with high susceptibility to dental caries without specific systemic disease;
Patients with inflammatory and/or ulcerative lesions in the oral cavityxe2x80x94either acute, chronic or recurrent; and
Any other patient, including patients with sensitive teeth, and those who wish to strengthen the teeth against dental caries and promote better oral healthxe2x80x94by combining a fluoride treatment with the supersaturated solution mouthwash.
For remineralising use, the supersaturated solutions should be used at least twice and up to ten times per day at a time when no food or drink is to be taken for at least 30 minutes after rinsing. If in combination with fluoride gel, the supersaturated solution is to be used after the fluoride treatment. In use, the preferred supersaturated solutions of this invention are believed to form, in the oral cavity with saliva when present, a mixture having 4.7-5 mM calcium; and 3-3.3 mM phosphate; at pH 6.9-7.1.
Cancer or BMT patients may require around five treatments per day. In cases of severe mucositis, the supersaturated solutions may be used as often as twelve times per day. Usually from 15 to 40 ml of the final, supersaturated solution is required per treatment comprising two-part rinsing. For example, in the case of a 20 ml treatment, the patient rinses first with about 10 ml of the supersaturated solution for about one minute, expectorates, and then repeats this procedure.
Remineralisation following the preventative treatment program mentioned before may be complete in xe2x80x98normalxe2x80x99 patients after approximately 2 weeks of twice-daily treatments followed by about one week of once-daily treatments; however, treatment may be continued thereafter. Cancer or BMT patients may need to continue treatment indefinitely or at least until resumption of normal salivary function after which treatment would follow the pattern for xe2x80x98normalxe2x80x99 patients.
Therefore, the present invention yet further provides a method of (a) remineralizing teeth; (b) preventing or relieving mucositis in subjects in need of such treatment; and (c) preventing oral cavity infection in a patient with an impaired immune system, which method comprises periodically rinsing the oral cavity with a supersaturated solution as described hereinbefore.